Basic Training: Focus on Focus (page 2)

Back focus
Back focus is typically an issue when you are videotaping two people standing together but not centered in the frame. The camera looks for an object in the very center to focus on, misses the two people to the sides and focuses on the wall behind them.

Not enough light
Today's camcorders are very sensitive to low light, but not having enough light will still send your camera hunting.

Rocking
When your camera is unsure of the focus or faced with an object that is constantly in slight motion, like a child on a swing, the focus may rock back and forth. Typically, this appears as slight back-and-forth motion exhibited by the lens' front element. The camera is ignorant of the depth of field and will try to focus, even when the depth of field is several feet in either direction. For this reason, sometimes it may be desirable to switch to manual focus or switch the auto focus off after the camera has focused itself on a well-illuminated subject.

Rules are made to be broken. Typically, you want the sharpest focus you can get. But there are times when you may NOT want sharp focus on a subject. One common technique is the use of "soft" focus to hide skin blemishes or wrinkles. You can use a "soft focus" adapter or the old Hollywood technique of shooting with a nylon stocking over the lens. The 1960's TV show Star Trek had a well-known habit of using soft focus to identify women as glamorous.

Another technique might be a POV shot demonstrating that a character is groggy or has been hit in the head or drugged. John Brahm uses out-of-focus POV shots to demonstrate the plight of hyper-nearsighted librarian Burgess Meredith after he loses his glasses in the classic Twilight Zone episode, Time Enough At Last.

One focus horror story comes from the 1962 film The Manchurian Candidate. In a critical scene, the director mismeasured the distance between the camera and Frank Sinatra's eyes. The singer delivered the scene, but the processed film revealed that the focus area was actually six inches past the star's eyes and the scene could not be re-shot. Luck won out, though, and the element in focus was the rank on Sinatra's military uniform, which caused audiences to change their own focus. Instead of focusing on his eyes, they focused on his collar, thinking "This is a military man; what does that mean about the words he is saying?" Later, film critics congratulated director John Frankenheimer on his clever use of focus, unaware that it was entirely unintentional.

Good, sharp focus is critical to the overall success of your production. By understanding how focus works and when to use things like manual or auto focus and avoiding common focusing mistakes, you can improve the overall value of your final product.

Contributing editor Kyle Cassidy is a visual artist who writes extensively about technology.

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